This invention relates to component pocket tape feeding systems and more particularly to a component pocket tape feeding system which precisely aligns the component within the pocket for enabling retrieval of the component.
Automation of electronic assembly provides reduced costs and increased reliability. However, with such automation, the need to supply parts to automatic assembly devices arises. Thus, several prior art methods of providing precise alignment of components to enable retrieval by assembly apparatus have been devised. One method employs a flat tape within which precision holes are punched for receiving portions of the components, typically the component leads. Then, through precise feeding of the tape, the exact location of a particular component can be known because the component is precisely positioned relative to the tape. There are, however, drawbacks to this method. Most importantly the components must be precisely loaded with respect to the tape, leading to expensive production. Further, it is necessary to provide complex machines to precisely form the holes in the tape as well as to ensure that components are accurately positioned within the preformed holes. Such an arrangement often leaves the component leads exposed and subject to damage. Automated part retrieving machines typically need to have the part positioned to within plus or minus 1/1000th of an inch to avoid having to reposition the part when it is picked up. With the previously discussed flat tape method, machines to precision load the tape must be able to place components into the tape to within 5/10,000th of an inch tolerance.
As an attempt to avoid the costs attendant with the previously discussed method, component manufacturers often will opt to perform manual unloading of the component tape wherein the component tape is not loaded with any particular precision. The individual components are removed from the tape and are placed within feeder trays which are then supplied to an assembly machine and the feeder trays provide the desired precise positioning of the parts. However, this method results in high labor costs.
Another problem with the previously discussed film tape is that the method is not adapted to surface mount devices which typically do not have leads extending downwardly that fit within precision formed holes in the carrier tape. Also, the surface mount device components may be fragile and may have extending portions needing protection from damage which might result from contact with a hard surface. Employing the prior art film tape does not provide such protection and could lead to deformation of sensitive component portions.
As an attempt to provide improved automated feeding of surface mount devices, a pocket component tape has been developed wherein the tape is provided with a pocket which receives the part. A top cover layer is then applied to hold the part within the pocket during storage and transit. However, many of the same problems attendant with the heretofore used tapes also arise with the pocket component tape. Namely, the part must either be precisely positioned within the component tape pocket, leading to expensive loading costs, or the components must be manually removed from the pocket tape and placed into assembly trays for retrieval.
Another method for removing parts from the component tape employs an expensive vision system. This system employs computer vision to ascertain the position and orientation of the part. Then, a mechanism is positioned to retrieve the part from its location and reposition the part to a known orientation for further use in the assembly process.
Thus, while several methods of providing components have been employed, typically the components are not precisely placed within a carrier, and the part is removed from the carrier pocket and then precisely aligned either manually or through use of an expensive vision and pattern recognition system. Alternatively, if the part is precisely aligned within the carrier, the cost of loading parts is high or else the methods are not suitable to surface mount devices.